Endless type carrier with type fingers connected by an endless strip and interposed viscous damping blocks

ABSTRACT

For employment in an on-the-fly printer wherein printing is accomplished by selectively actuating print hammers aligned along a print line to drive a print-receiving member against opposed moving type elements, a type-supporting member wherein type elements are mounted on individual resilient tongues of a moving endless belt to travel along the print line and wherein damping means is provided to suppress vibration of the type-carrying tongues in the plane of the print line.

United States Patent [1 1 Torrens [451 Ju1y24, 1973 1 ENDLESS TYPE CARRIER WITH TYPE FINGERS CONNECTED BY AN ENDLESS STRIP AND INTERPOSED VISCOUS DAMPING BLOCKS [75] Inventor:

[7 3] Assignee: Societe Industrielle Honeywell Bull,

Paris, France [22] Filed: Oct. 12, 1971 [21] Appl. No.: 188,057

Christian Torrens, Paris, France [30] Foreign Application Priority Data Oct. 20, 1970 France 7037768 [52] U.S. Cl. 101/111, 197/58 [51] Int. Cl B4Ij H20 [58] Field of Search 101/93 C, 111

[56] References Cited UNITED STATES PATENTS 3,638,565 2/1972 Dreiza 101/111 3,216,348 11/1965 Oldenburg et al. 101/111 X 3,670,647 6/1972 Funk et a1 101/93 C X 3,416,442 12/1968 Brown et a1 3,133,497 5/1964 Martin 101/111 X 3,041,964 7/1962 Simpson et al. 101/111 Primary Examiner-Robert E. Pulfrey Assistant Examiner-E. Mv Coven Attorney-Ronald T. Reiling et a1.

[57] ABSTRACT For employment in an on-the-fly printer wherein printing is accomplished by selectively actuating print hammers aligned along a print line to drive a print-receiving member against opposed moving type elements, a typesupporting member wherein type elements are mounted on individual resilient tongues of a moving endless belt to travel along the print line and wherein damping means is provided to suppress vibration of the type-carrying tongues in the-plane of the print line.

9 Claims, 7 Drawing Figures PMENTED SHEET 2 (IF 2 INVENTOR CHRISTIAN TORRENS BACKGROUND OF THE INVENTION The present invention relates to an improvement to the apparatus disclosed in the French Patent application PV 174,294, filed in France Nov. 19, 1968, and the corresponding US. Patent application Ser. No. 876,913, filed Nov. 14, 1969 by R..l. Migoux et al. for ENDLESS TYPE SUPPORT BAND FOR MOVEA- BLE-TYPE PRINTING MACHINE, both of said applications being assigned to the assignee of the present invention.

A steel endless type-carrying belt of the kind provided with type-carrying tongues along its upper edge is employed by being stretched over two pulleys. It is necessary that such belt pass in front of a fixed platen or anvil, parallel to a print line of printing positions with a maximum constant velocity determined by the number of characters to be printed per second as provided by the specifications of the printer.

The optimal shape and dimensions of each typecarrying tongue are determined so that when a type element at the end of a tongue receives the impact of a print hammer through the intermediary of at least one web of paper and an inking ribbon, such tongue deforms to enable the struck type element to remain opposite a printing position for the duration of the impact of the hammer. As soon as the type element is released, the associated tongue begins to vibrate in its plane at its fundamental period of resonance, which is not necessarily the same for all the tongues.

Because of a particular type element can be struck both when it passes in front of a printing position N and when it passes next in front of the following position N+l, the minimum striking period for a type element may be very short. It is apparent that under these conditions, in order to obtain correct spacing for all of the printed characters, it is absolutely necessary to halt the vibration of each type-carrying tongue in an interval less than such minimum striking period.

This problem of damping is further accentuated when, having determined the maximum velocity with which the type-carrying belt is to pass along the print line, it is desired to employ striking mechanisms which are less costly but relatively slow. With such striking mechanisms, the impact of the hammer may last an appreciable fraction of the minimum striking period, for example 100 microseconds. This results in two unfavorable factors. On one hand, the amplitude of deflection of the struck tongue increases in proportion to the arrest time of the type element and, on the other hand, the increased impact duration correspondingly reduces the interval available for damping the vibration before the next potential impact.

Pursuant to the above-mentioned patent applications, a damping means for the type-carrying tongues which consists of an elastomer strip fastened toward the ends of the tongues can be suitable under certain conditions of employment. However, under conditions of maximum stress certain disadvantages may appear. First the elastomer strip may not withstand the stresses it experiences, so that either it will break or some of the tongues will become detached from the belt by local separation thereof. Second, this solution does not provide sufficient independent between adjacent tongues,

since it is desirable that the deflection of the struck tongue not be reflected in the adjacent tongues.

Accordingly, it is an object of the instant invention to overcome the above-mentioned disadvantages of the prior art type-carrying belts. The concept of the present invention is to provide each type-carrying tongue fomiing a part of an endless printing belt with an individual damping member. Each of these members, or damping blocks, is attached to a strip which must not follow the relative displacements of the ends of the tongues in relation to the endless printing belt.

SUMMARY OF THE INVENTION Consequently, in accordance with the objects of the instant invention, a metallic endless type-carrying belt is provided, which is intended to be driven at constant velocity by two pulleys of an on-the-fly printer provided with striking mechanisms. Such belt has alongside one of its edges a plurality of partially cutout tongues, each bearing at its free end a printing type element in relief. A damping strip, which is also endless, of a material with high elastic strength is provided. Each of a plurality of elastomer damping blocks is attached on one side thereof to a corresponding typecarrying tongue and on the other side thereof to said damping strip. the damping blocks are placed in such a position that the damping strip is disposed a distance below the level of the printing type elements.

The elastomer of the damping blocks must be se lected from among those providing viscous damping.

BRIEF DESCRIPTION OF THE DRAWING The invention will be described with reference to the accompanying drawing wherein:

FIG. 1 is a perspective view of the endless typecarrying belt of the invention;

FIGS. 2A, 2B and 2C are detailed views of a portion of the type-carrying belt of FIG. 1 in accordance with a first embodiment thereof; and

FIGS. 3, 4 and 5 are cross-sectional views of a portion of the type-carrying belt of the invention according to second, third and fourth embodiments respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT The basic endless type-carrying belt 10, of known type, in FIG. 1 is shown in the orientation in which it is mounted on two pulleys in a printer, the pulleys not being illustrated. However, the vertical axes of rotation 11 and 12 of such pulleys are shown. Belt 10 is provided with type-carrying tongues 13 along its entire upper edge. All of tongues 13 are identical and are spaced apart with a pitch P, for example of 3.91 mm. In the embodiment shown, however, belt 10 is provided with several complete sets of different characters, for example eight sets of 48 different characters or symbols, requiring 384 tongues 13.

The lower portion, or body, M of the endless belt has at least one welded seam, such as seam 15. Belt 10 is provided with synchronization holes 16 toward its lower edge, each of which is located, for example, in alignment with the axis of a slot separating two adjacent tongues 13.

The printing type elements 17 appear on the exterior face of belt 10 because it is presumrned that in front of the front portion of the belt are disposed an inking ribbon or a carbon ribbon, a print receiving member in the form of at least one wide web of paper, and a series of print hammers selectively actuable in known manner. As indicated in the above-mentioned applications, the ends of type-carrying tongues 13 pass in the front of and in contact with a fixed platen or anvil, not shown, disposed along the length of the print line. The linear velocity of the belt may be 6 m per second.

In accordance with the instant invention, a damping strip 18, which is shown to greater scale in FIGS. 2A-2C, as well as damping blocks 19, one for each type-carrying tongue 13, are added to a type-carrying belt 10.

Strip 18 and blocks 19 are positioned on the internal face of tongues 13; i.e., on the face which is opposite that on which type elements 17 are mounted. Strip 18 may be realized of steel foil of 0.05 to 0.15 mm thickness, whereas the thickness of belt 10 may be 0.15 mm.

Because of the presence of anvil 20, FIG. 2C, mentioned previously herein, the upper edge of strip 18 must'be suitably distant from the horizontal axis 21 of the printing type elements, for example 7 mm. If the length of tongues 13 to axis 21 is approximately 23 mm, the width of strip 18 may vary between approximately one-fourth and two-fifths of such length.

In the embodiment of FIG. 2C each damping block 19 is of uniform thickness, which may be between 0.5 and L5 mm. Blocks 19 must be made of elastic material and furnish viscous damping. Therefore, blocks 19 may be of an isobutylene-isoprene copolymer (butyl) or a suitable polyurethane. Each of blocks 19 is attached both to strip 18 and to a face of the corresponding tongue 13 by any appropriate bonding process, such as cementing or hot molding. The width of each of blocks 19 may be equal to the width of a tongue 13, as shown in FIG. 2B, or may be different thereform. Further, the cross-section of a block 19 may be trapezoidal, instead of rectangular.

Strip 18 clearly must comprise a seam, which is located preferably between two blocks 19. This seam may be made by end-to-end welding, overlapping, cementing, etc. The open length of strip 18 must be equal to that of type-carrying belt 10, whereby the tongues 13 undergo, without difficulty, a deflection toward the exterior in the curvilinear sections passing around the driving pulleys.

In accordance with the same concept of the typecarrying tongues, when a type element is struck by a print hammer, the flexibility of the corresponding tongue enables the deflection thereof in its plane, as explained above. FIG. 2A illustrates a tongue, which bears a type element with the character 0, deflected to its maximum deformation, which is attained exactly at the completion of the impact by a hammer. With the above-indicated belt velocity and a duration of arrest of the struck type element of I microseconds, for example when the body of the belt is moving toward the left in the drawing, the maximum deflection d at the level of the type elements may reach 0.6 mm.

Each damping block is intended to very rapidly halt the vibration of a type-carrying tongue as soon as the type element is released by the hammer.

It is apparent from FIG. 2A that the maximum deflection of a damping block at the level of the upper edge of strip 18 is clearly less than the maximum deflection d, and that such deflection at the lower level of the strip is even less, owing to the curvature of the tongue being considered.

The embodiment of FIG. 2C, indicating a uniform thickness of the damping blocks, is advantageous by reason of its simplicity of fabrication. However, it is apparent that the material of the block is poorly utilized since the lateral shearing stress is much greater at the upper level than at the lower level. The efficiency of the damping block is thereby reduced.

The embodiment of FIG. 3 is provided to remedy this defect. In this embodiment, the damping strip 22 can have the same dimensions as those of strip 18, but its rectilinear cross-section is inclined relative to that of tongues 13 because each damping block 23 decreases in thickness toward the bottom thereof. Thus, the thickness of blocks 23 can be selected to be maximum at the top and minimum at the bottom, whereby the shearing stress is nearly uniform over the entire height of a deflected block.

However, the embodiments shown in FIGS. 2C and 3 may demonstrate another defect, from the standpoint of the longitudinal motion, because strips 18 and 22 are not fully united to the body 14 of belt 10. Accordingly; when a type-carrying tongue is deflected to its maximum, the damping strip may transmit a perturbation to the adjacent tongues. This latter defect should be avoided as must as possible.

The embodiments of FIGS. 4 and 5 are directed toward eliminating the last-mentioned defect. In the two embodiments, the widths of strips 24 and 26 are increased so that the lower edges thereof reach nearly to the roots of type-carrying tongues 13.

In the embodiment of FIG. 4, the cross-section of strip 24 is again rectilinear and each block 25 has a decreasing thickness from top to bottom. Although the thickness of block 25 at the level of its lower edge theoretically may be zero, it is preferable that such thickness be adequate to assure the adherence of block 25 both to strip 24 and tongue 13. In this embodiment uniforrnity of the shearing stress over the entire height of a deflected block may be only approximate, but any relative longitudinal motion between strip 24 and the body 14 of the belt is virtually suppressed.

In the embodiment of FIG. 5, the dimensions and the materials of the elements are the same as those suitable for FIG. 4, with the difference that the cross-section of damping strip 26 is curvilinear. The generatrix of this cross-section may be an arc of a circle or any other curve even better adapted to obtain uniformity of the shearing stress over the entire height of a deflected block 27.

Damping strips 18, 22, 24 and 26 may be realized of a glass fabric which withstands well longitudinal tensile stresses.

I claim:

1. A metallic endless type-carrying belt intended to be driven at constant velocity by two pulleys of an on the-fly printer provided with striking print hammers, said belt having along one of its edges a plurality of partially cutout slots transverse to said belt length forming a plurality of tongues having roots at the unslotted portion of the belt and each bearing at its free end a printing type element in relief, wherein the improvement comprises: an endless damping strip of a material with high elastic strength and a plurality of separate damping blocks of a viscous elastic material one for each of said tongues, one side of each of said blocks being attached to a corresponding one of said type-carrying tongues and the other side of each of said blocks being attached to said damping strip, said blocks being attached to said tongues at a position locating the damping strip a distance below the level of said printing type elements which permits deflection of each typecarrying tongue in its plane during the impact by one of said print hammers.

2. The type-carrying belt of claim 1, wherein said strip and said damping blocks are attached on the face of said tongues opposite to the tongue face bearing said printing type elements.

3. The type-carrying belt of claim 2, wherein said damping blocks are made of a material providing viscous damping of vibrations.

4. The type-carrying belt of claim 3, wherein said damping block material is one of an isobutylaneisoprene copolymer or a polyurethane.

5. The type-carrying belt of claim 3, wherein said damping blocks are of uniform thickness.

6. The type-carrying belt of claim 3, wherein said damping blocks are of decreasing thickness from the edge of said strip closest to the type elements toward the roots of said type-carrying tongues.

7. The type-carrying belt of claim 6, wherein the width of said damping strip is such that its lower edge is disposed proximate to the roots of said type-carrying tongues.

8. The type-carrying belt of claim 7, wherein the cross section of said damping strip is curvilinear in a manner to provide uniformity of the shearing stress over an entire damping block.

9. The printing element of claim 1, wherein said damping strip comprises a metallic strip. 

1. A metallic endless type-carrying belt intended to be driven at constant velocity by two pulleys of an on-the-fly printer provided with striking print hammers, said belt having along one of its edges a plurality of partially cutout slots transverse to said belt length forming a plurality of tongues having roots at the unslotted portion of the belt and each bearing at its free end a printing type element in relief, wherein the improvement comprises: an endless damping strip of a material with high elastic strength and a plurality of separate damping blocks of a viscous elastic material one for each of said tongues, one side of each of said blocks being attached to a corresponding one of said type-carrying tongues and the other side of each of said blocks being attached to said damping strip, said blocks being attached to said tongues at a position locating the damping strip a distance below the level of said printing type elements which permits deflection of each type-carrying tongue in its plane during the impact by one of said print hammers.
 2. The type-carrying belt of claim 1, wherein said strip and said damping blocks are attached on the face of said tongues opposite to the tongue face bearing said printing type elements.
 3. The type-carrying belt of claim 2, wherein said damping blocks are made of a material providing viscous damping of vibrations.
 4. The type-carrying belt of claim 3, wherein said damping block material is one of an isobutylane-isoprene copolymer or a polyurethane.
 5. The type-carrying belt of claim 3, wherein said damping blocks are of uniform thickness.
 6. The type-carrying belt of claim 3, wherein said damping blocks are of decreasing thickness from the edge of said strip closest to the type elements toward the roots of said type-carrying tongues.
 7. The type-carrying belt of claim 6, wherein the width of said damping strip is such that its lower edge is disposed proximate to the roots of said type-carrying tongues.
 8. The type-carrying belt of claim 7, wherein the cross section of said damping strip is curvilinear in a manner to pRovide uniformity of the shearing stress over an entire damping block.
 9. The printing element of claim 1, wherein said damping strip comprises a metallic strip. 